1. Field of the Invention
The present invention relates to a substrate polishing apparatus and a substrate polishing method for polishing a surface of a substrate, such as a semiconductor substrate, by holding the substrate with a substrate holding mechanism, pressing the substrate against a polishing surface of a polishing pad on a polishing table, and causing relative movement between the surface of the substrate and the polishing surface of the polishing pad. The present invention also relates to an apparatus for regulating a temperature of the polishing surface of the polishing pad used in the substrate polishing apparatus.
2. Description of the Related Art
A chemical mechanical polishing (CMP) apparatus has been known as an apparatus for polishing a surface of a substrate, such as semiconductor substrate. Typically, this apparatus has a polishing table, a polishing pad attached to an upper surface of the polishing table, and a substrate holding mechanism (which will be hereinafter referred to as a top ring). The polishing pad provides a polishing surface for polishing the substrate. The substrate, to be polished, is held by the top ring and pressed against the polishing surface of the polishing pad, while slurry is supplied onto the polishing surface. The polishing table and the top ring are rotated to cause relative movement between the polishing surface and the surface of the substrate, thereby polishing and planarizing the surface of the substrate.
It is important for an approach to finer semiconductor device to uniformly polish the surface of the substrate in the CMP apparatus. To achieve uniform polishing of the surface of the substrate, there has been an attempt to regulate contact pressure of the substrate surface against the polishing surface so as to optimize pressure distribution within the surface of the substrate.
However, a polishing rate of the substrate surface is affected not only by the contact pressure on the polishing surface, but also by a temperature of the polishing surface, a concentration of the slurry supplied, and the like. Therefore, it is not possible to completely control the polishing rate only by regulating the contact pressure on the polishing surface. In particular, in a CMP process in which the polishing rate highly depends on the temperature of the polishing surface (e.g., in a case where a surface hardness of the polishing pad highly depends on the temperature thereof), the polishing rate varies from portion to portion of the substrate surface due to temperature distribution in the polishing surface. As a result, a uniform polishing profile cannot be obtained. Generally, the temperature of the polishing surface of the polishing pad is not uniform because of heat generation of the polishing surface itself due to contact with the surface of the substrate and due to contact with a retainer ring of the top ring provided for retaining the substrate, a variation in heat absorptivity of the polishing surface, flow behavior of the slurry supplied onto the polishing surface, and the like. Therefore, there are temperature differences in regions of the polishing surface.